As is known in the art, a transducer is a device or apparatus that converts non electrical physical parameters into electrical signals (i.e. current or voltage signals) having a value proportional to the value of the physical parameter being measured. Typical transducers provide a variation in an electrical resistance, inductance, or capacitance in response to a change in some physical parameter to be measured.
For example, a strain gauge may be provided by disposing a foil or wire in a region in which strain is to be measured. The electrical wire or foil is provided from a piezoresistive material. Thus, a change in the length and or cross-sectional area (i.e. mechanical deformation) of the foil or wire produces a change in the electrical resistance of the foil or wire.
The resultant change in electrical resistance of the foil or wire corresponds to a particular strain. A corresponding electrical signal is subsequently fed via an electrical line, for example, from the foil or wire to a detector and electronics where the signal is detected and processed to provide an indication of the corresponding level of strain. Thus, by measuring the change in resistance of the foil or wire to a calibration level of the strain gauge, the strain within the region to which the strain gauge is attached may be determined.
One problem with this approach however, is that electrical signal paths are subject to sources of noise which in some applications render the measurement system unusable. Furthermore, in those applications in which electrical based devices are disposed in potentially explosive environments such electrical based devices may be hazardous to use.